CloudStack VDC : Managing Backups and Snapshots
This guide explains how to use snapshots and backups in CloudStack, including how they differ, how to create and restore them, best practices, retention guidance, and troubleshooting tips.
Concepts and Definitions
Snapshots
A snapshot is a point-in-time copy of a CloudStack instance or volume (root or data disk). Snapshots capture the state of the volume at the time they are taken and can be used to create new volumes or to restore an existing volume.
Typical uses:
Short-term recovery from user error or minor data corruption on a volume.
Creating VM templates from a known-good state (via a root volume snapshot).
Cloning volumes for test, development, or staging environments.
Backups
A backup is a complete copy of a VM instance, stored using dedicated backup storage capacity. Backups can be taken manually (on-demand) or scheduled to run automatically on an hourly, daily, weekly, or monthly basis.
Each backup contains all volumes attached to the VM at the time the backup runs.
Only full backups are supported — incremental backups are not available.
Backups are stored on your allocated backup storage, separate from primary storage.
Important: CloudStack backups are full backups only. Every backup operation creates a complete copy of all protected volumes. Incremental backups are not supported. |
Key Differences: Snapshots vs Backups
Aspect | Snapshots | Backups |
Scope | Per-volume (root or data disk) or per-instance | Per-instance only |
Storage location | Created on Primary and Instantly moved to Secondary on Completion | Backup storage |
Backup type | Individual point-in-time captures per volume | Full backups only. Incremental backups are not supported. |
Best suited for | Short-term protection, quick rollback, template creation, volume cloning. | Long-term retention, disaster recovery, compliance. |
Considerations
Check your resource limits before creating snapshots or backups. Storage quotas and maximum snapshot counts can be found on the CloudStack dashboard under Storage.
Every backup is a full backup — plan your backup storage capacity accordingly.
Coordinate backup and snapshot activities with the application layer for database or transactional workloads to ensure data consistency.
Working with Snapshots
Creating a Volume Snapshot (On-Demand)
Important: Volume snapshots can only be created while the instance is powered off. Snapshot operations (both manual and scheduled) will fail if the instance is running. |
Power off the VM containing the volume you want to snapshot.
Navigate to Instances, select the VM, and open the Volumes tab — or navigate directly to Storage > Volumes.
Select the volume you want to snapshot.
Click the Create Snapshot option from the top-right menu of the volume details page.
Confirm the operation and wait for the snapshot task to complete. The status will update to indicate the snapshot is ready.
Note: Completed snapshots can be viewed from Storage > Volume Snapshots. For consistent snapshots of database or other transactional workloads, quiesce or pause writes before taking the snapshot where possible. |
Restoring a Volume from a Snapshot
There are two ways to recover data from a snapshot:
Option A – Create a New Volume from a Snapshot
Navigate to Storage > Volume Snapshots and locate the snapshot you want to use.
Verify the snapshot status is Complete and that it is associated with the correct source volume and zone.
Select the option to Create Volume from Snapshot.
Enter the required details and confirm. Wait for the volume creation task to complete.
The new volume can then be attached to any VM as needed.
Option B – Revert a Volume to a Snapshot
Important: Reverting a snapshot permanently overwrites all current data on the volume with the snapshot contents. This action cannot be undone. |
Power off the VM using the volume to prevent data inconsistency.
Navigate to Storage > Volume Snapshots and select the relevant snapshot.
Select the option to Revert Volume to Snapshot.
Confirm that you understand this will replace the current data on the volume.
Wait for the operation to complete, then power on the VM and validate the restored state.
Working with Backups
Assign an Instance to a Backup Offering
Before any backup tasks can be processed, each instance must be assigned to a backup offering. This is a one-time setup step per VM.
Navigate to Instances and open the details page of the VM you wish to back up.
From the top-right action menu, select Assign Instance to Backup Offering.
Select the appropriate backup offering to enable the instance for backup.
Creating an On-Demand Backup
Navigate to Instances and open the details page of the VM you want to back up.
From the top-right action menu, select Start Backup.
Enter a backup name and description when prompted.
Confirm and wait for the backup job to complete. Monitor the job status until it shows success.
Note: Completed backups can be viewed from the Backup submenu on the instance details page, or from Storage > Backups for an account-wide view. |
Configuring Scheduled Backups
Scheduled backups can be configured from the instance details page or from the Backup Schedules page in the main menu.
Open the VM details page and select Configure Backup Schedule from the action menu.
Select an interval type: Hourly, Daily, Weekly, or Monthly.
Configure the schedule timing and the number of backups to retain.
Save the schedule. The scheduled backup will now run automatically at the configured interval.
Note: If the Configure Backup Schedule option is not visible, ensure the instance has been assigned to a backup offering (see Assign an Instance ). |
Important: Because each scheduled run creates a full backup, ensure your backup storage capacity and retention settings align with your storage quota before enabling frequent schedules. |
Restoring from a Backup
CloudStack provides three restore options:
Option | Description |
Instance Restore | Overwrites the current instance, returning it to the backed-up state. |
Create New Instance | Creates a new VM instance from the backup, leaving the original intact. |
Restore and Attach | Restores individual volumes from the backup and attaches them to a VM. |
Restoring an Entire VM
Navigate to Storage > Backups, or open the Backup submenu on the original instance.
Locate the backup that corresponds to the point in time you want to restore. Review its timestamp and description to confirm.
Select the restore option and choose either Instance Restore or Create New Instance.
Optionally adjust instance configuration via Configure Instance before confirming.
Start the restore operation and monitor progress until complete.
Restoring Specific Volumes from a Backup
Navigate to the backup for the relevant VM.
Review the list of volumes included in the backup.
Select the specific volume you want to restore.
Choose the target instance to attach the recovered volume to and confirm.
Best Practices
When to Use Snapshots vs Backups
Use snapshots for quick, short-term protection of individual volumes — for example, before performing a risky change such as an OS upgrade or application patch.
Use backups for longer-term retention, disaster recovery, or compliance coverage for one or more VMs.
Use both mechanisms together to provide layered protection.
Consistency for Transactional Workloads
For databases, messaging systems, or other transactional workloads, quiesce the application or pause writes before taking a snapshot or backup where possible.
Schedule backups and snapshots during maintenance windows or periods of lower activity.
Retention and Storage Planning
Backup Retention
Because every backup is a full backup, total storage consumption grows proportionally with the number of retained backups and the protected data size.
Estimate the average size of your protected VMs and how that is expected to grow.
Define a retention policy that meets your regulatory and business requirements without exceeding your backup storage quota.
Contact support@zettagrid.com if you need assistance sizing your backup storage.
Snapshot Retention
Snapshots should generally be retained for shorter periods than backups.
Check the maximum snapshot count per account on the CloudStack dashboard under Storage.
Remove snapshots that are no longer required, especially after completing application maintenance.
Use snapshot policies (schedules) where available rather than relying solely on manual management.
Troubleshooting
Common Snapshot Issues
Symptom | Check |
Snapshot fails immediately | Confirm the instance is powered off. Volume snapshots will fail if the instance is running. |
Snapshot stuck in progress | Check CloudStack event logs for errors. Contact support with the VM ID, volume ID, and snapshot job ID. |
No snapshot option visible | Ensure secondary storage has been provisioned for your subscription (required to store snapshots). |
Common Backup Issues
Symptom | Check |
Backup fails to start | Confirm the instance has been assigned to a backup offering. |
Backup job fails | Check that backup storage quota has not been exceeded. Full backups consume significantly more space than incremental strategies. |
Restore fails or VM behaves unexpectedly after restore | Do not delete the original backups until the issue is fully understood and resolved. Contact support@zettagrid.com with the VM ID and backup job ID. |
Configure Backup Schedule not visible | The instance has not been assigned to a backup offering. Complete Step 1 first. |
Frequently Asked Questions
Are incremental backups supported?
No. CloudStack backups are full backups only. Every backup operation creates a complete, self-contained copy of all protected volumes for the VM.
Can I use snapshots instead of backups?
Snapshots are best suited for short-term, per-volume protection. Backups provide longer-term, per-VM retention and disaster recovery coverage. Use both mechanisms together based on your protection requirements.
Can I restore a single file from a backup or snapshot?
CloudStack snapshots and backups operate at the volume level. To recover a single file, restore or attach the relevant volume to a recovery VM and copy the file using standard operating system tools.
How many backups or snapshots should I keep?
The appropriate number depends on your business, compliance, and recovery objectives, as well as your available storage. Because all backups are full, retaining many copies can consume substantial space. Contact support@zettagrid.com for guidance on defining a backup and retention policy suited to your environment.
Where can I see how much backup storage I have used?
Navigate to the CloudStack dashboard and check the Storage section for your current backup storage usage and quota.